Poll: Hacker News to send emails on discussion thread

Many good discussions here, but its hard to keep track of through 'thread' or 'comments' feature. Why can't HN send an email everytime someone responds to a thread I am part of, or to a post that I made? Apparently the only posts that gets more discussion are the controversial ones (like the currently hot 'Mike Arrington got pissed!'). I would like to see more activity on other tech topics as well, and email will certainly help.